Field of the Invention
This invention relates to optical detectors. More specifically, the invention is a single-element optical detector system for imaging or sensing applications that detects and/or measures photo-induced electron transfer through a micro-scale electron conduction element (e.g., a carbon nanotube (CNT), a photoactive material having a low work function, or a combination of these two) that are spaced from a bias voltage screen through which radiation of interest passes.
In accordance with the present invention, an optical detector system includes an electrically resistive screen that is substantially transparent to radiation energy having a wavelength of interest. A voltage source is provided to apply a bias voltage to the screen. An electron transfer element (e.g., a low work function photoactive material, a carbon nanotube (CNT), or a CNT topped with a low work function photoactive material) has a first end and a second end with its first end spaced apart from the screen by an evacuated gap. When radiation energy passes through the screen with the bias voltage being applied thereto, transfer of electrons through the electron transfer element is induced from its first to its second end. A detector, electrically coupled to the second end of the electron transfer element, detects a quantity indicative of the electrons transferred through the electron transfer element. The optical detector system can operate as described for imaging applications and can be adapted for sensing applications by providing an analyte-sensitive, luminescent coating on the screen.